Moving robot, moving robot system, and method for moving to charging station of moving robot

ABSTRACT

The present specification relates to a moving robot, a moving robot system, and a method for moving to a charging system of the moving robot, wherein the moving robot determines a distance between the moving robot and the charging station based on a reception result of a transmission signal transmitted from the charging station to thereby determine a moving path for moving to the charging station based on the determined distance.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2019/009608, filed on Aug. 1, 2019, which claims the benefit of earlier filing date and rights of priority to U.S. Provisional application No. 62/714,088 filed on Aug. 3, 2018 and Korean Application No. 10-2019-0050961 filed on Apr. 30, 2019, the contents of which are all hereby incorporated by reference herein in their entirety.

BACKGROUND 1. Field

The present disclosure relates to a moving robot that autonomously travels, a moving robot system, and a method for moving to a charging station of the moving robot.

2. Description of the Related Art

Generally, a moving robot is a device that automatically performs a predetermined operation while traveling by itself in a predetermined area without a user's operation. The moving robot senses obstacles located in the area and performs its operations by moving close to or away from such obstacles.

Such a moving robot may include a cleaning robot that carries out cleaning while traveling in the predetermined area, as well as a moving robot that mows a lawn on a bottom of the predetermined area. Generally, lawn mower devices include a riding-type device that moves according to a user's operation to cut a lawn or perform weeding when the user rides on the device, and a work-behind type or hand type device that is manually pushed or pulled by the user to move and cut a lawn. However, since the lawn mower devices move and cut a lawn according to direct operations by a user, the user may inconveniently operate the device directly. Accordingly, researches have been conducted on a moving robot-type mower device including elements that cuts a lawn. However, since a moving robot operates outdoors as well as indoors, there is a need to set an area in which the moving robot is to move. In detail, since an outdoor area is an open space unlike an indoor area, the area in which the moving robot is to move needs to be designated in the outdoor area in advance, and the area needs to be limited so that the moving robot travels in a place in which the lawn is planted.

As a prior art of the lawn mower device, the Korean Laid-Open Patent Publication No. 10-2015-0125508 (disclosed on Nov. 9, 2015) (hereinafter referred to as prior art document 1) discloses technology of burying a wire in a lawn-planted area to set an area in which the moving robot is to move, to thereby control the moving robot to move in an inner area with reference to the wire. Then, a boundary for the moving robot is set based on a voltage value induced by the wire. However, although such a method for using a wire makes it easy to recognize a position of a boundary portion of a travel area and perform traveling, there is a limit in improving position recognition and traveling in a wide travel area within the boundary portion.

In addition, US Publication No. 2015-0150676 (published on Jun. 1, 2017) (hereinafter referred to as prior art document 1) discloses technology of installing a plurality of beacons at a boundary portion of a travel area, determining a relative position of a robot with respect to the plurality of beacons, based on signals transmitted from the plurality of beacons while the robot is traveling along a boundary, and storing coordinate information and using the coordinate information to determine a position. That is, in prior art document 2, the robot transmits and receives signals with the plurality of beacons provided in the boundary portion of the travel area in a distributed manner, the travel area is set based on a result of the transmission and reception, and thus, accurate travel area/position recognition is performed using relative position information with respect to the plurality of beacons. Accordingly, a restriction on position recognition that was a limit in prior art document 1 may be partially resolved.

In addition, since a moving robot for lawn mowing operates outdoors instead of indoors, there may be many constraints in traveling. For example, due to characteristics of a wide open outdoor area, it may be difficult to search for a position of a charging station and accurately determine a position of the moving robot. This may lead to constraints on performance of communication between the charging station and the moving robot. Thus, it may become difficult to determine a position via the communication. In addition, due to various factors such as terrain/objects, it may become difficult to travel to return to the charging station.

In order to solve such a problem, a method in which the moving robot performs traveling until it finds a position of the charging station or reaches a boundary area in which a travel area may be recognized, and thus, determines a position of the charging station according to a result of the traveling, and then, returns to the charging station was proposed. However, this method had a limit in that it was difficult for the moving robot to quickly return to the charging station in a wide outdoor environment. For example, as time for returning to the charging station increased due to unnecessary traveling, there were concerns that driving power might be discharged before the moving robot returns to the charging station, that the moving robot becomes further away from the charging station while traveling to find a position of the charging station, or the like.

That is, generally, return travel of the moving robot to the charging station was not accurately/properly/easily performed. Accordingly, driving power of the moving robot was not easily charged. Due to these problems, operation performance of a moving robot traveling in a wide outdoor environment was limited, and there was a limit in ensuring reliability, reliability, utilization, and effectiveness of the moving robot.

SUMMARY

Therefore, an aspect of the present disclosure is to overcome limitations of the related art described above.

In detail, an aspect of the present disclosure is to provide a moving robot, a moving robot system, and a method for moving to a charging station of the moving robot using specifications of communication between the moving robot and the charging station.

Also, an aspect of the present disclosure is to provide the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot, wherein the moving robot may determine a path for moving to the charging station even in a particular communication condition.

In addition, an aspect of the present disclosure is to provide the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot, wherein the moving robot may move to the charging station by determining an optimum path for moving to the charging station.

Particularly, an aspect of the present disclosure is to provide the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot, wherein the moving robot and the charging station respectively include one communication module to thereby quickly and accurately determine an optimum path for moving to the charging station in a communication condition in which communication is performed via the one communication module.

In addition, an aspect of the present disclosure is to provide the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot, whereby unnecessary traveling and time for moving to the charging station may be reduced.

In order to solve such problems described above, an aspect of the present disclosure is to provide the moving robot, the moving robot system, and the method for moving the moving robot to the charging station, wherein the moving robot determines a distance from the charging station based on a reception result of a transmission signal transmitted from the charging station, and determine a moving path for moving to the charging station based on the determined distance.

In detail, information about a distance between the moving robot and the charging station is estimated based on a result of a reception intensity of the transmission signal while the moving robot travels in a path having a predetermined pattern, a point nearest the charging station is determined based on a result of the estimation, and a moving path to the charging station is determined using a result of the determination.

Accordingly, even in a communication environment in which only reception intensity of the transmission signal may be determined, a point nearest the charging station may be determined based on the reception intensity, and thus, the moving path to the charging station may be determined.

That is, the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot according to the present disclosure are configured such that, when the moving robot moves to the charging station, the moving robot travels from a current position in a present pattern, estimates information about a distance between the moving robot and the charging station based on a reception result of a transmission signal received from the charging station while the moving robot travels in the pattern, determines a moving path for moving to the charging station based on the distance information, and thus, moves to the charging station according to the moving path.

An aspect of the present disclosure is to provide the moving robot, the moving robot system, and the method of moving to the charging station of the moving robot configured such that the moving robot determines the moving path by determining a direction in which the charging station is located and a point nearest the charging station and moves to the charging station via the determined moving path to thereby solve the above-described problems.

The technical features herein may be implemented as a control element of a moving robot, a moving robot system, a control system of a moving robot, a method for controlling a moving robot, and a method for moving to a charging station of a moving robot, a method for determining a moving path of a moving robot, a control element of a lawn mower robot, a lawn mower robot, a lawn mower robot system, a control system of the moving robot, a control method of a lawn mower robot, a method for moving to a charging station of a lawn mower robot, or a method for controlling traveling of a lawn mower robot, etc. In this specification, embodiments of a moving robot, a moving robot system, and a method for moving to a charging station of the moving robot using the above-described technical features are provided.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is provided a moving robot including a main body, a driving unit that moves the main body, a receiver that receives a transmission signal transmitted from a charging station in a travel area, and a controller that controls traveling of the main body by controlling the driving unit so that the main body travels in the travel area, based on at least one selected from a reception result of the transmission signal and an area map that is pre-stored, wherein the controller, when the controller controls the main body to move to the charging station, estimates information about a distance between the main body and the charging station based on the reception result of the transmission signal received while the main body travels in a pattern that is preset, by controlling the main body to travel at a current position in the pattern, and controls the main body to move to the charging station according to the moving path by determining a moving path for moving to the charging station based on the distance information.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is also provided a moving robot system including a charging station that is provided in a travel area and transmits a transmission signal for determining position information, and a moving robot that travels in the travel area based on at least one selected from a reception result of the transmission signal and a prestored area map, wherein the moving robot, when the moving robot returns to the charge station, travels at a current position according to a path that is preset, estimates information about a distance between the moving robot and the charging station based on a reception result of the transmission signal received during the traveling according to the pattern, determines a moving path for moving to the charging station based on the distance information, and moves to the charging station via the moving path.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is also provided a method for moving to a charging station of a moving robot, wherein the moving robot includes a main body, a driving unit that moves the main body, a receiver that receives a transmission signal transmitted from a charging station in a travel area, and a controller that controls traveling of the main body by controlling the driving unit so that the main body travels in the travel area, based on at least one selected from a reception result of the transmission signal and an area map that is pre-stored, the method including starting pattern traveling at a current position according to a preset closed-loop pattern, determining information about a distance between the main body and the charging station based on a reception result of the transmission signal during the pattern traveling, setting a point nearest the charging station, among points of a path of the pattern traveling, as a first point, returning to the current position by finishing the pattern traveling, moving from the current position to the first point, and moving from the first point to the charging station.

A moving robot, a moving robot system, and a method for moving to a charging station of the moving robot, according to the present disclosure, may be implemented as a control element of a lawn mower robot, a lawn mower robot system, a control system of a lawn mower robot, a method for controlling a lawn mower robot, and a method for moving to a charging station of a lawn mower robot. However, the technology disclosed in this specification is not limited thereto and may be implemented as any robot cleaner to which the technical idea of the above-described technology can be applied, a control element that controls a robot cleaner, a robot cleaning system, a method for controlling a robot cleaner, or the like.

Effects of the Disclosure

A moving robot, a moving robot system, and a method for moving to a charging station of the moving robot according to the present disclosure may have such an effect that the moving robot may determine a path for moving to the charging station and move to the charging station using specifications for communications between the moving robot and the charging station, by determining a moving path to the charging station based on a result of receiving a transmission signal while the moving robot travels in a path having a predetermined pattern.

In particular, the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot according to the present disclosure may have such an effect that the moving robot may move/return to the charging station by overcoming restrictions caused by the communication specifications, by determining a direction in which the charging station is located and a moving path to the charging station based on an estimation result of distance information according to a reception result of the transmission signal.

In addition, the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot according to the present disclosure may have such an effect that the moving robot may move to the charging station by determining an optimum path for moving to the charging station, by determining a point nearest the charging station according to the reception result of the transmission signal.

Accordingly, the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot according to the present disclosure may have such an effect that unnecessary traveling and time for moving to the charging station may be reduced, and thus, the moving robot may quickly and accurately move to the charging station.

That is, the moving robot, the moving robot system, and the method for moving to the charging station of the moving robot according to the present disclosure have such an effect that movement to the charging station may be performed accurately, quickly, appropriately, and efficiently even in an environment where a communication restriction occurs.

As a result, the moving robot, the moving robot system, and the moving robot moving method according to the present disclosure have such effects that limitations of the prior art may be resolved, and accuracy, reliability, stability, applicability, efficiency, effectiveness, and utilization in the technical field of moving robots for lawn mowing in which a signal transmission element is utilized/adopted may be enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a configuration diagram (a) illustrating one embodiment of a moving robot and a moving robot system according to the present disclosure.

FIG. 1B is a configuration diagram (a) of the moving robot according to the present disclosure.

FIG. 1C is a configuration diagram (b) of the moving robot according to the present disclosure.

FIG. 1D is a configuration diagram (c) of the moving robot according to the present disclosure.

FIG. 2 is a conceptual diagram illustrating one embodiment of a travel area of the moving robot according to the present disclosure.

FIG. 3A is a conceptual diagram illustrating a traveling principle of the moving robot and the moving robot system according to the present disclosure.

FIG. 3B is a conceptual diagram illustrating a signal flow between devices to determine positions of the moving robot and the moving robot system according to the present disclosure.

FIG. 4 is a detailed configuration diagram of the moving robot according to the present disclosure.

FIG. 5A is an exemplary view (a) for explaining an example of moving to a charging station according to an embodiment of the moving robot and the moving robot system according to the present disclosure.

FIG. 5B is an exemplary view (b) for explaining an example of moving to the charging station according to an embodiment of the moving robot and the moving robot system according to the present disclosure.

FIG. 6A is an exemplary view (a) illustrating an example of a pattern according to an embodiment of the moving robot and the moving robot system according to the present disclosure.

FIG. 6B is an exemplary view (b) illustrating an example of a pattern according to an embodiment of the moving robot and the moving robot system according to the present disclosure.

FIG. 6C is an exemplary view (c) illustrating an example of a pattern according to an embodiment of the moving robot and the moving robot system according to the present disclosure.

FIG. 6D is an exemplary view (d) illustrating an example of a pattern according to an embodiment of the moving robot and the moving robot system according to the present disclosure.

FIG. 7 is an example view illustrating a process of moving a position according to an embodiment of the moving robot and the moving robot system according to the present disclosure.

FIG. 8 is an example view illustrating a process of determining a moving path according to an embodiment of the moving robot and the moving robot system according to the present disclosure.

FIG. 9 is a flowchart illustrating a sequence for a method for moving to the charging station of the moving robot according to the present disclosure.

DETAILED DESCRIPTION

Hereinafter, embodiments of a moving robot, a moving robot system, and a method for moving the moving robot to a charging station according to the present disclosure will be described in detail with reference to the accompanying drawings, and the same reference numerals are used to designate the same/like components and redundant description thereof will be omitted.

In describing technologies disclosed in the present disclosure, if a detailed explanation for a related known function or construction is considered to unnecessarily divert the gist of the technologies in the present disclosure, such explanation has been omitted but would be understood by those skilled in the art. It should be noted that the attached drawings are provided to facilitate understanding of the technical idea disclosed in this specification, and should not be construed as limiting the technical idea by the attached drawings.

First, a moving robot (hereinafter referred to as a robot) according to the present disclosure will be described.

The robot 100 may refer to a robot capable of autonomous traveling, a lawn mowing moving robot, a lawn mower robot, a lawn mower device, or a moving robot for lawn mowing. As shown in FIG. 1A, the robot 100 travels in a travel area 1000 that is set, and cuts a lawn in the travel area 1000. The robot 100 may operate based on driving power charged by a charging station 500 provided in the travel area 1000 to thereby travel in the travel area 1000 and cut a lawn. When the robot 100 that operates based on driving power supplied by the charging station 500 moves to the charging station 500 after the robot 100 travels in the travel area 1000, the robot 100 may receive a transmission signal transmitted from a signal transmission modules 510 included in the charging station 500, and move to the charging station 500 based on a result of the reception of the transmission signal.

As shown in FIG. 1B, the robot 100 includes a main body 10, a driving unit 11, a receiver 12, and a controller 20, wherein the driving unit 11 moves the main body 10, the receiver 12 receives the transmission signal transmitted from the charging station 500 provided in the travel area 1000, and the controller 20 controls traveling of the main body 10 by controlling the driving unit 11 so that the main body 10 travels in the travel area 1000, based on at least one selected from a result of the reception of the transmission signal and a prestored area map.

That is, as the controller 20 controls the driving unit 11 so that the robot 100 travels in the travel area 1000 based on at least one selected from the result of the reception by the receiver 12 and the prestored area map, the robot 100 travels in the travel area 1000.

As such, in the robot 100 including the main body 10, the driving unit 11, the receiving unit 12, and the controller 20, when the controller 20 controls the main body 10 to move to the charging station 500, the controller 20 controls the main body 10 to travel at a current position in a preset pattern. Thus, the controller 20 estimates information about a distance between the main body 10 and the charging station 500 based on a reception result of the transmission signal received while the main body 10 travels in the preset pattern, and determines a moving path to the charging station 500 based on the distance information to thereby control the main body 10 to move to the charging station 500 according to the moving path.

That is, when the robot 100 moves to the charging station 500 after traveling in the travel area 1000, the robot 100 estimates the distance information based on the reception result of the transmission signal received when the robot 100 travels in the pattern, and thus, moves to the charging station 500 according to the moving path determined based on the distance information.

As shown in FIGS. 1C and 1D, the robot 100 may be an autonomous traveling robot including the main body 10 that is provided to be capable of moving and cutting a lawn. The main body 10 forms an outer shape of the robot 100 and includes one or more elements performing operations such as traveling of the robot 100 and cutting of a lawn. The main body 10 includes the driving unit that may move the main body 10 in a desired direction and rotate the main body 10. The driving unit 11 may include a plurality of rotatable driving wheels. Each of the driving wheels may individually rotate so that the main body 10 may rotate in a desired direction. In detail, the driving unit 11 may include at least one main driving wheel 11 a and an auxiliary wheel 11 b. For example, the main body 10 may include two main driving wheels 11 a, and the two main driving wheels 11 a may be installed on a rear lower surface of the main body 10.

The robot 100 may travel by itself in the travel area 1000 shown in FIG. 2. The robot 100 may perform a particular operation during traveling. Here, the particular operation may be an operation of cutting a lawn in the travel area 1000. The travel area 1000 is a target area in which the robot 100 is to travel and operate. A predetermined outside/outdoor area may be provided as the travel area 1000. For example, a garden, a yard, or the like in which the robot 100 is to cut a lawn may be provided as the travel area 1000. The charging station 500 for charging driving power for the robot 100 may be installed at one point of the travel area 1000. The robot 100 may be charged with driving power by docking on the charging station 500 installed in the travel area 1000.

The travel area 1000 may be provided as a boundary area 1200 that is predetermined, as shown in FIG. 2. The boundary area 1200 corresponds to a boundary line between the travel area 1000 and an outside area 1100, and the robot 100 may travel in the boundary area 1200 not to deviate to the outside area 1100. In this case, the boundary area 1200 may be formed to have a closed curved shape or a closed-loop shape. Also, in this case, the boundary area 1200 may be defined by a wire 1200 formed to have a shape of a closed curve or a closed loop. The wire 1200 may be installed in an arbitrary area. The robot 100 may travel in the travel area 1000 having a closed curved shape formed by the installed wire 1200.

As shown in FIG. 2, a transmitter 200 may be provided in the travel area 1000. At least one transmission device 200 may be provided in the travel area 1000. At least three transmission devices 200 may be preferably provided in a distributed manner. The at least one transmission device 200 is a signal generation element configured to transmit a signal via which the robot 100 determines position information. The at least one transmission device 200 may be installed in the travel area 1000 in a distributed manner. The robot 100 may receive a signal transmitted from the transmission device 200 to thereby determine a current position of the robot 100 based on a result of the reception or determine position information regarding the travel area 1000. In this case, in the robot 100, the receiver 12 may receive the transmitted signal. The transmission device 200 may be provided in a periphery of the boundary area 1200 of the travel area 1000. In this case, the robot 100 may determine the boundary area 1200 based on an arrangement position of the transmission device 200 in the periphery of the boundary area 1200. The transmission device 200 may include an inertial measurement unit (IMU) sensor that detects posture information of the transmission device 200. The IMU sensor is a sensor including at least one selected from a gyro sensor, an acceleration sensor, and an altitude sensor. The IMU sensor may be a sensor that senses posture information of the transmission device 200. Accordingly, the transmission device 200 may sense posture information of the transmission device 200 according to a present arrangement state via the IMU sensor. Further, when a posture is changed according to a change of a position, the transmission device 200 may sense the change of the posture according to the change of the position via the IMU sensor.

The robot 100 that travels in the travel area 1000 and cuts a lawn as shown in FIG. 2 may operate according to a traveling principle shown in FIG. 3A, and a signal may flow between devices for determining a position as shown in FIG. 3B.

As shown in FIG. 3A, the robot 100 may communicate with a terminal 300 moving in a predetermined area, and travel by following a position of the terminal 300 based on data received from the terminal 300. The robot 100 may set a virtual boundary in a predetermined area based on position information received from the terminal 300 or collected while the robots 100 is traveling by following the terminal 300, and set an internal area formed by the virtual boundary as the travel area 1000. When the boundary area 1200 and the travel area 1000 are set, the robot 100 may travel in the travel area 1000 not to deviate from the boundary area 1200. According to cases, the terminal 300 may set the boundary area 1200 and transmit the boundary area 1200 to the robot 100. When the terminal 300 changes or expands an area, the terminal 300 may transmit changed information to the robot 100 so that the robot 100 may travel in a new area Also, the terminal 300 may display data received from the robot 100 on a screen and monitor operation of the robot 100.

The robot 100 or the terminal 300 may determine a current position by receiving position information. The robot 100 and the terminal 300 may determine a current position based on the transmission signal transmitted from the charging station 500 or a global positioning system (GPS) signal obtained using a GPS satellite 400. For example, a distance between the robot 100 and the charging station 500 may be measured based on a reception strength, a reception direction, reception time, or the like of the transmission signal. Then, based on this, a current position may be determined by determining a position of the charging station 500 in the travel area 1000. Alternatively, the GPS satellite 400 may receive a GPS signal transmitted from the GPS module in the charging station 500 and a current position of the charging station 500 is determined based on the GPS signal to thereby determine a current position.

In addition, when the transmitter 200 is provided in the travel area 1000, the robot 100 and the terminal 300 may determine a current position based on a signal for position information transmitted from the transmitter 200. Here, when signals are received from a plurality of transmitters 200, positions of the robot 100 and the plurality of transmitters 200 may be determined by comparing results of receiving the signals from the plurality of transmitters 200 with each other, respectively, to thereby determine positions of the robot 100 and the plurality of transmitters 200. Alternatively, a current position of the robot 100 may be determined by receiving a GPS signal transmitted from the GPS module included in the transmission device 200 and determining a position of the transmission device 200 based on the GPS signal. In addition, positions of the robot 100 and the plurality of transmission devices 200 may be accurately determined by determining distances between the plurality of transmission devices 200 based on respective positions of the plurality of transmission devices 200. The robot 100 and the terminal 300 may preferably determine a current position by receiving signals transmitted from three transmission devices 200 and comparing the signals with each other. That is, three or more transmission devices 200 may be preferably provided in the travel area 1000.

The robot 100 sets one certain point in the travel area 1000 as a reference position, and then, calculates a position while the robot 100 is moving as a coordinate. For example, an initial starting position of the robot 100, that is, one of positions of the plurality of charging stations 500 may be set as a reference position. Alternatively, a position of one of the plurality of transmitters 200 may be set as a reference position to calculate a coordinate in the travel area 1000. The robot 100 may set an initial position of the robot 100 as a reference position in each operation, and then, determine a position of the robot 100 while the robot 100 is traveling. With reference to the reference position, the robot 100 may calculate a traveling distance based on rotation times and a rotational speed of the driving unit 11, a rotation direction of the main body 10, etc. to thereby determine a current position in the travel area 1000. Even when the robot 100 determines a position of the robot 100 using the GPS satellite 400, the robot 100 may determine the position using a certain point as a reference position.

As shown in FIG. 3B, the robot 100 may determine a current position based on position information transmitted from the GPS satellite 400 or the charging station 500. The position information may be transmitted in the form of a GPS signal, an ultrasound signal, an infrared signal, an electromagnetic signal, or an ultra-wideband (UWB) signal. A transmission signal transmitted from the charging station 500 may preferably be a UWB signal. That is, the transmission signal may be a UWB signal transmitted from a signal transmission module 510 in the charging station 500. Accordingly, the robot 100 may receive the UWB signal transmitted from the charging station 500, and determine a current position of the robot 100 based on the UWB signal. The charging station 500 may also include the GPS module to transmit a GPS signal. In this case, the GPS signal transmitted from the charging station 500 may be received by the GPS satellite 400. In addition, the GPS satellite 400 may transmit, to the robot 100, a result of receiving the GPS signal from the charging station 500.

As shown in FIG. 4, the robot 100 operating as described above includes the main body 10, the driving unit 11, the receiver 12, and the controller 20, and travel in the travel area 1000 based on the result of the reception by the receiver 12 and the prestored area map. Also, the robot 100 may further include at least one selected from a communication unit 13, a data unit 14, an input/output unit 15, an obstacle detection unit 16, a weeding unit 17, and a sensing unit 18.

The driving unit 11 is a driving wheel included in a lower part of the main body 10, and may be rotationally driven to move the main body 10. That is, the driving unit 11 may be driven so that the main body 10 travels in the travel area 1000. The driving unit 11 may include at least one driving motor to move the main body 10 so that the robot 100 travels. For example, the driving unit 11 may include a left wheel driving motor for rotating a left wheel and a right wheel driving motor for rotating a right wheel.

The driving unit 11 may transmit information about a driving result to the controller 20, and receive a control command for operation from the controller 20. The driving unit 11 may operate according to the control command received from the controller 20. That is, the driving unit 11 may be controlled by the controller 20.

The receiver 12 may include at least one sensor module that transmits and receives the transmission signal. The receiver 12 may include a signal sensor module that receives the transmission signal transmitted from the charging station 500. The signal sensor module may transmit a signal to the charging station 500. When the charging station 500 transmits a signal using a method selected from an ultrasound method, a UWB method, and an infrared method, the receiver 12 may include a sensor module that transmits and receives an ultrasound signal, a UWB signal, or an infrared signal, in correspondence with this. The receiver 12 may preferably include a UWB sensor. As a reference, UWB radio technology refers to technology using a very wide frequency range of several GHz or more in baseband instead of using a radio frequency (RF) carrier. UWB wireless technology uses very narrow pulses of several nanoseconds or several picoseconds. Since pulses emitted from such a UWB sensor are several nanoseconds or several picoseconds long, the pulses have good penetrability. Thus, even when there are obstacles in a periphery of the UWB sensor, the receiver 12 may receive very short pulses emitted by other UWB sensors.

When the robot 100 travels by following the terminal 300, the terminal 300 and the robot 100 include the UWB sensors, respectively, and thus, transmit or receive the UWB signals with each other through the UWB sensors. The terminal 300 may transmit the UWB signal to the robot 100 through the UWB sensor included in the terminal 300. The robot 100 may determine a position of the terminal 300 based on the UWB signal received through the UWB sensor, and thus, move by following the terminal 300. In this case, the terminal 300 operates as a transmitting side and the robot 100 operates as a receiving side. When the transmitter 200 includes the UWB sensor and transmits a signal, the robot 100 or the terminal 300 may receive the signal transmitted from the transmitter 200 through the UWB sensor included in the robot 100 or the terminal 300. At this time, a signaling method performed by the transmission device 200 may be identical to or different from signaling methods performed by the robot 100 and the terminal 300.

The receiver 12 may include one or more UWB sensors. When two UWB sensors are included in the receiver 12, for example, provided on left and right sides of the main body 10, respectively, the two USB sensors may receive signals, respectively, and compare a plurality of received signals with each other to thereby calculate an accurate position. For example, according to a position of the robot 100, the charging station 500, or the terminal 300, when a distance measured by a left sensor is different from a distance measured by a right sensor, a relative position between the robot 100 and the charging station 500 or the terminal 300, and a direction of the robot 100 may be determined based on the measured distances.

The receiver 12 may transmit the reception result of the transmission signal to the controller 20, and receive a control command for operation from the controller 20. The receiver 12 may operate according to the control command received from the controller 20. That is, the receiver 12 may be controlled by the controller 20.

The communication unit 13 may communicate with a communication device that is to communicate with the robot 100, using a wireless communication method. For example, the communication unit 13 may communicate with at least one selected from the transmitter 200, the terminal 300, and the GPS satellite 400. The communication unit 13 is connected to a predetermined network and may communicate with an external server or the terminal 300 that controls the robot 100. When the communication unit 13 communicates with the terminal 300, the communication unit 13 may transmit a generated map to the terminal 300, receive a command from the terminal 300, and transmit data regarding an operation state of the robot 100 to the terminal 300. The communication unit 13 may include a communication module such as wireless fidelity (Wi-Fi), wireless broadband (WiBro), or the like, as well as a short-range wireless communication module such as Zigbee, Bluetooth, or the like, to transmit and receive data. The communication unit 13 may communicate with the GPS satellite 400 via the terminal 300 that communicates with the GPS satellite 400. In addition, the communication unit 13 may further include a GPS module that transmits or receives a GPS signal to/from the GPS satellite 400 to communicate with the GPS satellite 400. When the communication unit 13 communicates with the GPS satellite 400, the GPS satellite 400 may receive a GPS signal transmitted from at least one transmitter 200 or the charging station 500 provided in the travel area 1000, and transmit a result of the reception of the GPS signals to the communication unit 18. That is, when the communication unit 13 communicates with the GPS satellite 400 that receives a GPS signal from the transmitter 200 or the charging station 500, the communication unit 18 may receive the result of the reception of the GPS signal from the GPS satellite 400.

The communication unit 13 may transmit information about a result of the communication to the controller 20, and receive a control command for operation from the controller 20. The communication unit 13 may operate according to the control command received from the controller 20. That is, the communication unit 13 may be controlled by the controller 20.

The data unit 14 is a storage element that stores data readable by a microprocessor, and may include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a read only memory (ROM) a random access memory (RAM), CD-ROM, a magnetic tape, a floppy disk, or an optical data storage device. In the data unit 14, a received signal may be stored, reference data to determine an obstacle may be stored, and obstacle information regarding a detected obstacle may be stored. In the data unit 14, control data that controls operation of the robot 100, data according to an operation mode of the robot 100, collected position information, and information about the travel area 1000 and the boundary area 1200 may be stored.

The input/output unit 15 may include input elements such as at least one button, a switch, a touch pad, or the like, and output elements such as a display unit, a speaker, or the like to receive a user command and output an operation state of the robot 100.

The input/output unit 15 may transmit information about an operation state to the controller 20 and receive a control command for operation from the controller 20. The input/output unit 15 may operate according to a control command received from the controller 20. That is, the input/output unit 15 may be controlled by the controller 20.

The obstacle detection unit 16 includes a plurality of sensors to detect obstacles located in a traveling direction. The obstacle detection unit 16 may detect an obstacle located in front of the main body 10, that is, in a traveling direction of the main body 10 using at least one selected from a laser sensor, an ultrasonic sensor, an infrared sensor, and a three-dimensional (3D) sensor. The obstacle detection unit 16 may further include a cliff detection sensor installed on a rear surface of the main body 10 to detect a cliff.

In addition, the obstacle detection unit 16 may include a camera for detecting an obstacle by photographing a front. The camera is a digital camera, and may include an image sensor (not shown) and an image processing unit (not shown). The image sensor is a device that converts an optical image into an electrical signal. The image sensor includes a chip in which a plurality of photodiodes are integrated. A pixel may be an example of a photodiode. Charges are accumulated in respective pixels by an image formed on a chip by the light passing through the lens, and the charges accumulated in the respective pixels are converted into an electrical signal (for example, a voltage). A charge-coupled device (CCD) sensor and a complementary metal oxide semiconductor (CMOS) sensor are well known as image sensors. In addition, the camera may include an image processing unit (a digital signal processor (DSP)) for processing a captured image.

The obstacle detection unit 16 may transmit information about a result of the detection to the controller 20, and receive a control command for operation from the controller 20. The obstacle detection unit 16 may operate according to the control command received from the controller 20. That is, the obstacle detection unit 16 may be controlled by the controller 20.

The weeding unit 17 cuts grass on a bottom during traveling. The weeding unit 17 includes a brush or a blade that cuts a lawn, and may mow a law on the bottom through rotation.

The weeding unit 17 may transmit information about a result of operation to the controller 20 and receive a control command for operation from the controller 20. The weeding unit 17 may operate according to the control command received from the controller 20. That is, the weeding unit 17 may be controlled by the controller 20.

The sensing unit 18 may include at least one sensor that senses information about a posture and operation of the main body 10. The sensing unit 18 may include at least one selected from an inclination sensor that detects movement of the main body 10 and a speed sensor that detects a driving speed of the driving unit 11. The inclination sensor may be a sensor that senses posture information of the main body 10. When the inclination sensor is inclined forward, backward, leftward or rightward against the main body 10, the inclination sensor may sense the posture information of the main body 10 by calculating an inclined direction and an inclination angle. A tilt sensor, an acceleration sensor, or the like may be used as the inclination sensor. In a case of the acceleration sensor, any of a gyro type sensor, an inertial type sensor, and a silicon semiconductor type sensor may be used. In addition, various sensors or devices capable of detecting movement of the main body 10 may be used. The speed sensor may be a sensor for sensing a driving speed of a driving wheel in the driving unit 11. When the driving wheel rotates, the speed sensor may sense the driving speed by detecting rotation of the driving wheel.

The sensing unit 18 may transmit information about a sensing result to the controller 20, and receive a control command for operation from the controller 20. The sensing unit 18 may operate according to a control command received from the controller 20. That is, the sensing unit 18 may be controlled by the controller 20.

The controller 20 may include a central processing unit to control all operations of the robot 100. The controller 20 may determine position information in the travel area 1000 via the receiver 12 and the communication unit 13 to thereby control the main body 10 to travel in the travel area 1000 via the driving unit 11. The controller 20 may also control functions/operations to be performed via the data unit 14, the input/output unit 15, the obstacle detection unit 16, the weeding unit 17, and the sensing unit 18.

The controller 20 may control input/output of data and control the driving unit 11 so that the main body 10 travels according to settings. The controller 20 may independently control operations of the left wheel driving motor and the right wheel driving motor by controlling the driving unit 11 to thereby control the main body 10 to travel rotationally or in a straight line.

The controller 20 may set the boundary area 1200 of the travel area 1000 based on position information received from the terminal 300 or position information determined based on the transmission signal received from the charging station 500. The controller 20 may also set the boundary area 1200 of the travel area 1000 based on position information that is collected by the controller 20 during traveling. The controller 20 may set a certain area of a region formed by the set boundary area 1200 as the travel area 1000. The controller 20 may set the boundary area 1200 in a closed-loop form by connecting discontinuous position information in a line or a curve, and set an inner area within the boundary area 1200 as the travel area 1000. When the travel area 1000 and the border area 1200 corresponding thereto are set, the controller 20 may control traveling of the main body 10 so that the main body 10 travels in the travel area 1000 and does not deviate from the set boundary area 1200. The controller 20 may determine a current position based on received position information and control the driving unit 11 so that the determined current position is located in the travel area 1000 to thereby control traveling of the main body 10.

In addition, according to obstacle information input by the obstacle detection unit 16, the controller 20 may control traveling of the main body 10 to avoid obstacles and travel. In this case, the controller 20 may reflect the obstacle information in prestored area information regarding the travel area 1000 to thereby modify the travel area 1000.

As the controller 20 determines a current position of the main body 10 based on at least one selected from the result of the reception by the receiver 12, a result of the communication by the communication unit 13, and the result of the sensing by the sensing unit 18, and controls the driving unit 11 so that the main body 10 travels in the travel area 1000 according to the determined position, the robot 100 having a configuration shown in FIG. 4 may travel in the travel area 1000.

While the robot 100 travels in the travel area 1000 shown in FIG. 1A, the robot 100 may perform set operations. For example, while the robot 100 is traveling in the travel area 1000, the robot 100 may cut a lawn on a bottom of the travel area 1000.

In the robot 100, the main body 10 may travel according to driving of the driving unit 11. The main body 10 may travel as the driving unit 11 is driven to move the main body 10.

In the robot 100, the driving unit 11 may move the main body 10 according to driving of driving wheels. The driving unit 11 may move the main body 10 by driving the driving wheels so that the main body 10 may perform traveling.

In the robot 100, the receiver 12 may receive the transmission signal transmitted from the charging station 500 provided in the travel area 1000, while the robot 100 is traveling. Here, the charging station 500 may include at least one signal transmission module 510, and transmit the transmission signal via the signal transmission module 510. The receiver 12 may include at least one signal sensor module that receives the transmission signal, and thus, receive the transmission signal. While the main body 10 is traveling in the travel area 1000, the receiver 12 may receive the transmission signal in real time. That is, the charging station 500 may transmit the transmission signal in real time, and the receiver 12 may receive the transmission signal in real time during traveling. Thus, the receiver 12 may receive the transmission signal each time when a position of the main body 10 is changed according to the traveling. Here, the transmission signal may be transmitted in a predetermined form. In addition, as the transmission signal is transmitted from a position in which the charging station 500 is provided, that is, from a fixed position of the charging station 500, a reception sensitivity of the transmission signal may vary depending on a position of the main body 10. That is, a reception result of the transmission signal may vary depending on positions in which the transmission signal is received, that is, a position of the main body 10, and the robot 100 may determine a current position of the main body 10 based on the transmission signal of which a reception result varies depending on reception positions of the transmission signal. For example, when the main body 10 travels from one point to another point, distances between the charging station 500 and the main body 10 are measured at the one point and the other point, respectively, based on the reception result obtained while the main body 10 travels from the one point to the another point, and it is determined that the main body 10 moved from the one point to the another point based on the measured distances. Thus, a current position of the main body 10 may be determined.

The controller 20 in the robot 100 may determine a position of the main body 10 based on the result of the reception by the receiver 12 and the prestored area map during traveling, and control the driving unit 11 to thereby control traveling of the main body 10 so that the main body 10 travels in the travel area 1000. Here, the prestored area map is a map of the travel area 1000. An arrangement position of the charging station 500 and the boundary area 1200 may be designated on the prestored area map. The area map may be prestored in the robot 100. For example, the prestored area map may be prestored in the data unit 14. The prestored area map may be pre-generated according to at least one selected from a previous traveling history of the robot 100, a position of the charging station 500, and a user setting for the robot 100, and prestored in the robot 100. The controller 20 may measure a position of the charging station 500 and a distance between the main body 10 and the charging station 500 based on the reception result, and determine a current position of the main body 10 based on the measured distance. In addition, the controller 20 may measure a distance by which the main body 10 has traveled, based on at least one selected from the result of the communication by the communication unit 13 and the result of the sensing by the sensing unit 18, and determine a current position of the main body 10 based on the measured distance. The controller 20 may control traveling of the driving unit 11 so that the main body 10 travels in the travel area 1000 according to the determined current position. That is, according to the determined current position, the controller 20 may control traveling of the main body 10 by controlling driving of the main body 10 so that the main body 10 does not deviate from the boundary area 1200. The controller 20 may also control operation of the main body 10 so that the main body 10 performs set operation.

As such, the robot 100 including the driving unit 11, the receiver 12, and the controller 20 may be configured such that the receiver 12 includes one signal sensor module to transmit or receive the transmission signal with one signal transmission module 510 included in the charging station 500. That is, the robot 100 may be configured in such an embodiment that the charging station 500 includes one signal transmission module 510 and transmits the transmission signal via the one signal transmission module 510, and the receiver 12 includes one signal sensor module and receives the transmission signal via the one signal sensor module. Accordingly, as the robot 100 receives one transmission signal through the one signal sensor module, the robot 100 may sense only intensity of the transmission signal. That is, the controller 20 may control traveling of the main body 10 so that the main body 10 moves to the charging station 500 along the moving path, by determining the moving path based on a result of the sensing of only the intensity of the one transmission signal.

As such, the controller 20 that controls traveling of the main body 10 controls the main body 10 to travel in the travel area 1000, and then, move to the charging station 500. That is, the controller 20 may control the driving unit 11 so that the main body 10 travels in the travel area 1000, and then, return to the charging station 500.

When the controller 20 controls the main body 10 to move to the charging station 500, the controller 20 controls the main body 10 to travel at a current position CP in a pattern P that is preset, to thereby control the main body 10 to move to the charging station 500 based on the reception result of the transmission signal obtained when the main body 10 travels in the pattern P, as shown in FIGS. 5A and 5B. In detail, while the main body 20 is traveling in the pattern P, the controller 20 estimates information about a distance between the main body 10 and the charging station 500 based on the reception result of the transmission signal received from the charging station 500, determines a moving path for moving to the charging station 500 based on the distance information, and thus, controls the main body 10 to move to the charging station 500 along the moving path. That is, when the robot 100 moves to the charging station 500, the robot 100 performs pattern traveling at the current position CP according to the pattern P, determines the moving path based on the reception result according to the pattern traveling, and thus, move to the charging station 500 along the moving path.

The pattern P shown in FIGS. 5A and 5B may be a traveling pattern for determining the moving path. The pattern P may be an operation criterion preset for a return mode so that the robot 100 performs the return mode for returning to the charging station 500. The pattern P may be set in a form of a particular figure. For example, the pattern P may have a form such as a circle shown in FIG. 6A, a triangle as shown in FIG. 6B, or an oval shown in FIGS. 6C and 6D. Accordingly, when the main body 10 travels in the pattern P, the main body 10 may travel in a form of the pattern shown in FIGS. 6A to 6D. The pattern P may be set as a pattern path PP for determining the moving path with reference to the current position CP. The pattern P may be a pattern having the current position CP as both a start point □ and an end point X. That is, the pattern P may be a pattern in which the start point □ matches the end point X. Accordingly, the robot 100 may start traveling at the current position CP according to the pattern P, and then, return to the current position CP to finish traveling according to the pattern P. The pattern P may be a pattern forming one or more closed curved surfaces. The pattern P may be a pattern forming one closed curved surface shown in FIGS. 6A to 6D. Accordingly, the pattern path PP of the pattern P may be a single path in one direction that does not include an intersection point. The pattern P may be a circular pattern having a predetermined radius r, as shown in FIG. 6A. When the pattern P is set as the circular pattern having the predetermined radius r as shown in FIG. 6A, the robot 100 may travel along the pattern path PP having a circular shape and receive the transmission signal. Accordingly, the reception result of the transmission signal may vary depending on each time/point.

When the main body 10 moves to the charging station 500, the controller 20 may control the driving unit 11 so that the main body 10 starts traveling at the current position CP according to the pattern P, and then, return to the current position CP and finish the traveling according to the pattern P. While the controller 20 controls the main body 10 to travel in the pattern P, the controller 20 may control the driving unit 11 so that the main body 10 moves to the charging station 500 along the moving path, by estimating the distance information based on the reception result of the transmission signal received via the receiver 12 and determining the moving path for moving to the charging station 500 based on the distance information. Thus, the main body 10 may move to the charging station 500 along the moving path.

The controller 20 may estimate the distance information at respective points on a path according to the pattern P based on the reception result during the traveling in the pattern P, determines the moving path based on the distance information at the respective points, and control the main body 10 to move to the charging station 500 according to the moving path. That is, the controller 20 may determine the moving path based on the distance information in the entire pattern path PP.

As such, the controller 20 that determines the moving path by estimating the distance information at the respective points of the path according to the pattern P based on the reception result during the traveling in the pattern P may determine a path from one point of the pattern P to the charging station 500 as the moving path. When the controller 20 determines the moving path, the controller 20 may determine the moving path to minimize a moving distance to the charging station 500. That is, the controller 20 may determine a path via which a distance to the charging unit 500 is minimized as the moving path. For example, a point in the pattern path PP nearest the charging station 500 may be determined, and the moving path may be determined according to a result of the determination. The controller 20 may determine the moving path to minimize a moving distance to the charging station 500, based on the distance information at the respective points. In this case, the controller 20 may determine a path from a point to the charging station 500 as the moving path, the point having the distance information as being nearest the charging station 500 among the respective points. That is, the controller 20 may determine a path from a point to the charging station 500 as the moving path, the point having the distance information as being nearest the charging station 500, and thus, the moving path to the charging station 500 is minimized. For example, when the main body 10 travels in the pattern P shown in FIGS. 5A and 5B, a path I from a point ∘ to the charging station 500 may be determined as the moving path, wherein the point ∘ is nearest the charging station 500 in the pattern path PP, and thus, the distance information of the point ∘ is estimated as being nearest the charging station 500.

The controller 20 may set the point ∘ having the distance information as being nearest the charging station 500 among the respective points as a first point P1, and set a center point • of the pattern P as a second point P2. For example, when traveling starts in the pattern P, a coordinate of the current position may be set to (r, 0) according to a radius of the pattern P and a coordinate of the center point • is set to (0, 0), and thus, a coordinate of the first point P1 may be set to (r, φ) with reference to the coordinate of the current position and the coordinate of the center point •. The controller 20 may set the first point P1 and the second point P2 to thereby determine the path

corresponding to a line including the first point P1 and the second point P2 as the moving path. That is, the moving path

may include a linear path in which a line connecting the first point P1 to the second point P2 extends to the charging station 500. Accordingly, as positions of the first point P1, the second point P2, and the charging station 500 are placed on one line, a distance of the moving path may be minimized. At this time, the controller 20 may set a point Δ having the distance information as being farthest from the charging station 500 as a third point P3, and thus, set an intermediate point • between the first point P1 and the third point P3 as the second point P2. In addition, the controller 20 may set the point ∘ having the distance information as being nearest the charging station 500, among the respective points, as the first point P1, set the point Δ having the distance information as being farthest from the charging station 500, among the respective points, as the third point P3, and thus, determine the path

corresponding to a line including the first point P1 and the third point P3 as the moving path. Thus, by determining the moving path with reference to the line including the first point P1, the moving path may be determined so that a moving distance to the charging station 500 is minimized.

After the main body 10 finishes the traveling according to the pattern P, the controller 20 may control the main body 10 to move from the current position CP to the point P1 having the distance information as being nearest the charging station 500 via the center point P2 of the pattern P, and then, move from the point P1 having the distance information as being nearest the charging station 500 to the charging station 500 according to the moving path. That is, as shown in FIG. 7, when the main body 10 returns to the current position CP after traveling from the current position CP along the pattern path PP of the pattern P1, the controller 20 may control traveling of the main body 10 so that the main body 10 moves in a sequence from the current position CP to the center point P2, from the center point P2 to the first point P1, and then, from the first point P1 to the charging station 500 to thereby move to the charging station 500 along the moving path. In this case, the controller 20 may control the traveling of the main body 10 so that the main body 10 moves to the charging station 500 using the coordinates of the first point P1, the second point P2 and the current position CP. For example, when the main body 10 travels from the current position CP in the pattern P, the controller 20 may control the main body 10 to travel in the pattern P based on a coordinate of the current position CP, and when the main body 10 moves from the current position CP to the center point P2 and the first point P1, the controller 20 may control the main body 10 to move to the center point P2 and the first point P1 based on respective coordinates of the second point P2 and the first point P1 preset/stored while the main body 10 travels in the pattern P.

As such, when the controller 20 that controls the main body 10 to move to the point P1 having the distance information as being nearest the charging station 500, via the center point P2 of the pattern P, and move from the point P1 having the distance information as being nearest the charging station 500 to the charging station 500 according to the moving path controls the main body 10 to move to the point P1 having the distance information as being nearest the charging station 500, the controller 20 may control the main body 10 to move by a radius r of the pattern P by rotating a traveling direction in a direction toward the center point P2 by 90 degrees, and then, move by the radius r of the pattern P by rotating the traveling direction in a direction toward the point P1 having the distance information as being nearest the charging station 500, in correspondence with an angle difference 8 between the center point P2 and the point P1. That is, when the main body 10 moves from the current position CP to the second point P2, the controller 20 controls the main body 10 to move by the radius r of the pattern P by rotating a traveling direction at the current position CP in a direction toward the second point P2 by 90 degrees, and when the main body 10 moves from the second point P2 to the first point P1, the controller 10 may control traveling of the main body 20 so that the main body 20 moves by the radius r of the pattern P, by rotating a traveling direction at the second point P2 in a direction toward the first point P1. In this case, the controller 20 may control the main body 10 to move to the charging station 500 based on coordinate information of each of the current position CP, the first point P1, and the second point P2 preset/stored while the main body 10 travels in the pattern P.

As such, the controller 20 that controls traveling of the main body 10 by determining the moving path so that the main body 10 moves to the charging station 500 according to the moving path may determine the moving path so that a traveling direction of the main body 10 corresponds to a predetermined range with reference to the charging station 500. For example, as shown in FIG. 8, the controller 20 may determine the moving path

′ so that a target point of the moving path

′ corresponds to a predetermined range R with reference to the charging station 500. That is, when the controller 20 determines the moving path, the controller 20 may determine the moving path by applying a predetermined offset to a target point of the moving path so that the target point of the moving path corresponds to a predetermined range R with reference to the charging station 500. Accordingly, when the robot 100 moves to the charging station 500 along the moving path, the robot 100 may move to a position corresponding to the predetermined range R with reference to the charging station 500. As such, when the controller 20 determines that the moving path

′ so that a traveling direction of the main body 10 corresponds to the predetermined range R with reference to the charging station 500, the controller 20 may control the main body 10 to move to a position corresponding to the predetermined range R with reference to the charging station 500, and then, move from the position corresponding to the predetermined range R to the charging station 500 along the boundary area 1200. That is, when the robot 100 determines the moving path

′ so that a traveling direction of the main body 10 corresponds to the predetermined range R with reference to the charging base 500, the main body 10 may move to the position within the predetermined range R along the moving path

′, and then, move from the position corresponding to the predetermined range R to the charging station 500 along the boundary area 1200.

The above-described embodiments of the robot 100 may be applied to a moving robot system and a method for moving to a charging station of the moving robot that will be described below. In addition, embodiments of the moving robot system and the method for moving to a charging station of the moving robot may be also applied to the robot 100.

Hereinafter, a moving robot system (hereinafter referred to as a system) according to the present disclosure will be described.

As shown in FIG. 1A, the system 1 is a system including the robot 100 and the charging station 500, wherein the robot 100 cuts a lawn in the travel area 1000 and the charging station 500 communicates with the robot 100 and charges the robot 100 with driving power in the charging system 500. The system 1 may be applied to all systems including the charging station 500 and the robot 100. Here, the robot 100 may be the robot 100 described above. That is, the system 1 may be a traveling/control/operation system of a moving robot that cuts a lawn in the travel area 1000.

The system 1 includes the charging station 500 and the robot 100, wherein the charging station 500 is provided in the travel area 1000 and transmits a transmission signal for determining position information, and the robot 100 travels in the travel area 1000 based on at least one selected from a reception result of the transmission signal and an area map that is pre-stored. Here, the transmission signal may be a UWB signal of which a reception result varies depending on a receiving position. That is, in the system 1, the charging station 500 and the robot 100 may transmit and receive the transmission signal that is a UWB signal.

In the system 1, at least one charging station 500 may be provided in the travel area 1000. The charging station 500 may charge the robot 100 with driving power. The charging station 500 may be a station where the robot 100 waits for traveling. Accordingly, before the robot 100 starts traveling or after the robot 100 finishes traveling, the robot 100 may dock on the charging station 500 to wait for traveling and be charged by the driving power.

The charging station 500 may communicate with the robot 100 via the transmission signal. The charging station 500 may include at least one transmission module 510, and transmit the transmission signal to the robot 100 via the one signal transmission module 510. In an embodiment of the system 1 according to the present disclosure, the charging station 500 may include the one signal transmission module 510 to thereby transmit the transmission signal to the robot 100 via the one signal transmission module 510. The charging station 500 may transmit the transmission signal to the robot 100 while the robot 100 is traveling. While the robot 100 is traveling in the travel area 1000, the charging station 500 may transmit the transmission signal to the robot 100 in real time. That is, the charging station 500 may transmit the transmission signal to the robot 100 in real time, and the robot 100 may receive the transmission signal in real time during traveling to thereby receive the transmission signal each time when a position of the robot 100 is changed according to the traveling. Here, the transmission signal may be transmitted in a predetermined form.

In the system 1, the robot 100 may operate based on driving power charged by the charging station 500 provided in the travel area 1000, and thus, travel in the travel area 1000 and cut a lawn. As shown in FIG. 1B, the robot 100 may include the main body 10, the driving unit 11, the receiver 12, and the controller 20, wherein the driving unit 11 moves the main body 10, the receiver 12 receives the transmission signal transmitted from the charging station 500 in the travel area 1000, and the controller 20 controls traveling of the main body 10 by controlling the driving unit 11 so that the man body 10 travels in the travel area 1000 based on at least one selected from a reception result of the transmission signal and the area map. That is, as the controller 20 controls the driving unit 11 to travel in the travel area 1000 based on at least one selected from the result of the reception by the receiver 12 and the area map, the robot 100 may travel in the travel area 1000.

The robot 100 may communicate with the charging station 500 using the transmission signal. The robot 100 may include at least one signal sensor module to receive the transmission signal through the signal sensor module. In an embodiment of the system 1 according to the present disclosure, the robot 100 may include one single signal sensor module to receive the transmission signal via the one signal sensor module. The robot 100 may receive the transmission signal from the charging station 500 transmitted from the charging station 500 while the robot 100 is traveling. While the robot 100 is traveling in the travel area 1000, the robot 100 may receive the transmission signal in real time. That is, the charging station 500 may transmit the transmission signal to the robot 100 in real time, and the robot 100 may receive the transmission signal in real time during traveling to thereby receive the transmission signal each time when a position of the robot 100 is changed according to the traveling. Here, as the transmission signal is transmitted from a position in which the charging station 500 is provided, that is, from a fixed position, a reception sensitivity of the transmission signal may vary depending on a position of the robot 100. That is, a result of the reception of the transmission signal may vary depending on a reception position of the transmission signal, that is, a position of the main body 100. The robot 100 may determine a current position based on the transmission signal of which the reception result varies depending on a reception position of the transmission signal. For example, when the robot 100 travels from one point to another point, a current position of the robot 100 may be determined by measuring distances from the one point and the another point of the robot 100 to the charging station 500, respectively, based on the reception result of the transmission signal while the robot 100 travels from the one point to the another point, and then, determining that the robot 100 moved from the one point to the another point based on the measured distances.

In the system 1, when the robot 100 returns to the charging station 500 during traveling, the robot 100 travels at the current position CP in the preset pattern P as shown in FIGS. 5A and 5B, estimates distance information between the robot 100 and the charging station 500 based on the reception result of the transmission signal received during the traveling according to the pattern P, and determines a moving path for moving to the charging station 500 based on the distance information to thereby move to the charging station 500 according to the moving path. That is, in the system 1, the robot 100 estimates the distance information based on the reception result of the transmission signal obtained while the robot travels according to the pattern P, and return to the charging station 500 according to the moving path determined based on the estimated distance information. Here, the charging station 500 may include at least one signal transmission module 510, and transmit the transmission signal via the signal transmission module 510. The robot 100 may include at least one signal sensor module that receives the transmission signal, and thus, receive the transmission signal. Accordingly, as the robot 100 receives one transmission signal through the one signal sensor module, the robot 100 may sense only intensity of the transmission signal. That is, the robot 100 may determine the moving path based on a result of sensing only intensity of the transmission signal received while the robot 100 travels according to the pattern P, and move to the charging station 500 according to the moving path.

The pattern P shown in FIGS. 5A and 5B may be a traveling pattern for determining the moving path. The pattern P may have a shape such as a circle shown in FIG. 6A, a triangle shown in FIG. 6B, or an oval shown in FIGS. 6C and 6D. The pattern P may be set as the pattern path PP for determining the moving path with reference to the current position CP. The pattern P may be a pattern having the current position P as both the start point □ and the end point X. That is, the pattern P may be a pattern in which the start point □ matches the end point X. Accordingly, the robot 100 may start traveling at the current position CP according to the pattern P, and then, return to the current position CP to finish traveling according to the pattern P. The pattern P may be a pattern forming one or more closed curved surfaces. The pattern P may be a pattern forming one closed curved surface shown in FIGS. 6A to 6D. Accordingly, the pattern path PP of the pattern P may be a single path in one direction that does not include an intersection point. The pattern P may be a circular pattern having a predetermined radius r. When the pattern P is set as a circular pattern having the predetermined radius r as shown in FIG. 6A, the robot 100 may travel along the pattern path PP having a circular shape and receive the transmission signal. Accordingly, the reception result of the transmission signal may vary depending on each time/point.

When the robot 100 moves to the charging station 500, the robot 100 that determines the moving path by traveling along the pattern P may start traveling at the current position CP according to the pattern P, and then, return to the current position CP by thereby finish the traveling according to the pattern P. While the robot 100 travels along the pattern P, the robot 100 estimates the distance information based on the reception result of the transmission signal received while the robot 100 travels according to the pattern P, determine the moving path for moving to the charging station 500 based on the estimated distance information, and thus, move to the charging station 500 along the moving path. The robot 100 may estimate the distance information at respective points on a path according to the pattern P based on the reception result during the traveling according to the pattern P, and determine the moving path based on the distance information at the respective points, and move to the charging station 500 along the moving path. That is, the robot 100 may determine the moving path based on the distance information in the entire pattern path PP.

As such, the robot 100 that determines the moving path by estimating the distance information at the respective points on the path along the pattern P based on the reception result during traveling in the pattern P may determine the path from one point of the pattern P to the charging station 500 as the moving path. When the robot 100 determines the moving path, the robot 20 may determine the moving path to minimize a moving distance to the charging station 500. That is, the robot 100 may determine a path via which a distance to the charging unit 500 is minimized as the moving path. For example, a point in the pattern path PP nearest the charging station 500 may be determined, and the moving path may be determined according to a result of the determination. The robot 100 may determine the moving path to minimize a moving distance to the charging station 500, based on the distance information at the respective points. In this case, the robot 100 may determine a path from a point having the distance information as being nearest the charging station 500, among the respective points, to the charging station 500 as the moving path. That is, the controller 20 may determine a path from a point to the charging station 500 as the moving path, the point having the distance information as being nearest the charging station 500, and thus, the moving path to the charging station 500 is minimized. For example, when the main body 10 travels in the pattern P shown in FIGS. 5A and 5B, a path

from a point ∘ to the charging station 500 may be determined as the moving path, wherein the point ∘ is nearest the charging station 500 in the pattern path PP, and thus, the distance information of the point ∘ is estimated as being nearest the charging station 500.

The robot 100 may set the point ∘ having the distance information as being nearest the charging station 500 as the first point P1, and the center point • of the pattern P as a second point P2. For example, when traveling starts in the pattern P, a coordinate of the current position may be set to (r, 0) according to a radius of the pattern P and a coordinate of the center point • is set to (0, 0), and thus, a coordinate of the first point P1 may be set to (r, φ) with reference to the coordinate of the current position and the coordinate of the center point •. The robot 100 may set the first point P1 and the second point P2 to thereby determine the path

corresponding to a line including the first point P1 and the second point P2 as the moving path. That is, the moving path

may include a linear path in which a line connecting the first point P1 to the second point P2 extends to the charging station 500. Accordingly, as positions of the first point P1, the second point P2, and the charging station 500 are placed on one line, a distance of the moving path may be minimized. At this time, the controller 20 may set a point Δ having the distance information as being farthest from the charging station 500 as a third point P3, and thus, set an intermediate point • between the first point P1 and the third point P3 as the second point P2. In addition, the robot 100 may set the point ∘ having the distance information as being nearest the charging station 500 as a first point P1 and set the point Δ having the distance information as being farthest from the charging station 500 as the third point P3, among the respective points, and thus, determine the path

corresponding to a line including the first point P1 and the third point P3 as the moving path. Thus, by determining the moving path with reference to the line including the first point P1, the moving path may be determined to minimize a moving distance to the charging station 500.

After the main body 10 finishes the traveling according to the pattern P, the robot 100 may move from the current position CP to the point P1 via the center point P2 of the pattern P, and then, move from the point P1 to the charging station 500 according to the moving path, the point P1 having the distance information as being nearest the charging station 500. That is, as shown in FIG. 7, when the robot 100 returns to the current position CP after traveling from the current position CP along the pattern path PP of the pattern P1, the robot 100 may move in a sequence from the current position CP to the center point P2, from the center point P2 to the first point P1, and then, from the first point P1 to the charging station 500 to thereby move to the charging station 500 along the moving path. In this case, the robot 100 may move to the charging station 500 using the coordinates of the first point P1, the second point P2 and the current position CP. For example, when the robot 100 travels from the current position CP to the pattern P, the controller 20 controls the main body 10 to travel in the pattern P based on a coordinate of the current position CP, and when the robot 100 moves from the current position CP to the center point P2 and the first point P1, the robot 100 may move to the center point P2 and the first point P1 based on respective coordinates of the second point P2 and the first point P1 preset/stored while the robot 100 travels in the pattern P.

As such, when the robot 100 for controlling to move to the point P1 having the distance information as being nearest the charging station 500 via the center point P2 of the pattern P and move from the point P1 having the distance information as being nearest the charging station 500 to the charging station 500 according to the moving path moves to the point P1, the robot 100 may move by the radius r of the pattern P by rotating a traveling direction to a direction of the center point P2 by 90 degrees, and then, move by the radius r of the pattern P by rotating a traveling direction in a direction toward the point P1 by the radius r of the pattern P in correspondence with the angle difference 8 between the center point P2 and the point P1, wherein the point P1 has the distance information as being nearest the charging station 500. That is, when the robot 100 moves from the current position CP to the second point P2, the controller 100 moves by the radius r of the pattern P by rotating a traveling direction at the current position CP in a direction toward the second point P2 by 90 degrees, and when the main body 10 moves from the second point P2 to the first point P1, the robot 100 may move by the radius r of the pattern P, by rotating a traveling direction at the second point P2 in a direction toward the first point P1 in correspondence with the angle difference 8 between the center point P2 and the point P1. In this case, the robot 100 may move to the charging station 500 based on coordinate information of each of the current position CP, the first point P1, and the second point P2 preset/stored while the robot 100 travels in the pattern P.

As such, the robot 100 that moves to the charging station 500 along the moving path by determining the moving path may determine the moving path so that a traveling direction of the main body 10 corresponds to a predetermined range with reference to the charging station 500. For example, as shown in FIG. 8, the controller 20 may determine the moving path

′ so that a target point of the moving path corresponds to a predetermined range R with reference to the charging station 500. That is, when the robot 100 determines the moving path, the robot 100 may determine the moving path by applying a predetermined offset to a target point of the moving path so that the target point of the moving path corresponds to the predetermined range R with reference to the charging station 500. Accordingly, when the robot 100 moves to the charging station 500 along the moving path, the robot 100 may move to a position corresponding to the predetermined range R with reference to the charging station 500. As such, when the robot 100 determines that the moving path

′ so that a traveling direction of the main body 10 corresponds to the predetermined range R with reference to the charging station 500, the robot 100 may move to a position within the predetermined range R with reference to the charging station 500 according to the moving path

′, and then, move to the charging station 500 from the position corresponding to the predetermined range R along the boundary area 1200. That is, when the robot 100 determines the moving path

′ so that a traveling direction of the main body 10 corresponds to the predetermined range R with reference to the charging base 500, the main body 10 may move to the position corresponding to the predetermined range R, and then, move from the position corresponding to the predetermined range R to the charging station 500 along the boundary area 1200.

The above-described embodiments of the system 1 may be applied to the moving robot described above and a method for moving to a charging station of the moving robot which is to be described below. In addition, embodiments of the moving robot and the method for moving a charging station of the moving robot may be applied to the system 1.

Hereinafter, a method for moving to a charging station of the moving robot according to the present disclosure (hereinafter referred to as a moving method) will be described.

The moving method is a method for moving, by the robot 100 shown in FIGS. 1B to 1D and included in the system 1 of FIG. 1A, to the charging station 500. The moving method may be applied to the robot 100 and the system 1

The moving method may be a method for controlling movement of the robot 100 in the system 1.

The moving method may be a control method performed by the controller 20 included in the robot 100.

The moving method is a method for moving to the charging station 500 in an order shown in FIGS. 5A to 5B, the moving being performed by the robot 100 including the main body 10, the driving unit 11, the receiver 12, and the controller 20 as shown in FIG. 1B, wherein the driving unit 11 moves the main body 10, the receiver 12 receives the transmission signal transmitted from the charging station 500 in the travel area 1000, and the controller 20 controls traveling of the main body 10 by controlling the driving unit 11 so that the main body 10 travels in the travel area 1000, based on at least one selected from a reception result of the transmission signal and an area map that is prestored. The moving method may be applied to a method by which the controller 20 controls traveling of the robot 100 or a method by which the robot 100 in the system 1 moves to the charging station 500.

As shown in FIG. 9, the moving method may include starting pattern traveling at the current position CP according to the preset closed-loop pattern P (S10), determining information about a distance between the main body 10 and the charging station 500 based on the reception result of the transmission signal obtained during the pattern traveling (S20), setting a point nearest the charging station, among points in a path for the pattern driving, as the first point P1 (S30), returning to the current position CP after finishing the pattern traveling (S40), moving from the current position CP to the first point P1 (S50), and moving from the first point P1 to the charging station 500 (S60).

That is, the robot 100 may move to the charging station 500 in an order from the starting of the pattern traveling (S10), the determining of the distance information (S20), the setting to the first point P1 (S30), the returning to the current position CP (S40), the moving to the first point P1 (S50), and the moving to the charging station 500 (S60).

In the starting of the pattern traveling (S10), the robot 100 may start the patterning traveling from the current position CP according to the pattern P.

In the determining of the distance information (S20), the robot 100 may receive the transmission signal at respective points of the pattern path PP of the pattern P during the pattern traveling, and determine the distance information based on a result of the reception.

In the determining of the distance information (S20), the robot 100 may estimate the distance information at respective points of the pattern path PP based on the reception result obtained while the robot 100 travels along the pattern path PP, and thus, determine the distance information at the respect points.

That is, in the determining of the distance information (S20), the robot 100 may determine the distance information in the entire pattern path PP.

In the setting as the first point P1 (S30), the robot 100 may set the point ∘ having the distance information as being nearest the charging station 500, among the respective points of the pattern path PP, as the first point P1 during the pattern driving.

That is, in the setting as the first point P1 (S30), the robot 100 may determine the point ∘ having the distance information as being nearest the charging station 500, among the respective points of the pattern path PP, based on the reception result, and set the determined point ∘ having the distance information as being nearest the charging station 500 as the first point P1.

In the returning to the current position CP (S40), the robot 100 may travel along the pattern path PP and return to the current position CP to thereby finish the pattern driving.

In the moving to the first point P1 (S50), after the robot 100 finishes the pattern driving, the robot 100 may move from the current position CP to the first point P1.

In the moving to the first point P1 (S50), the robot 100 may move from the current position CP to the center point P2 of the pattern P, and then, move from the center point P2 to the first point P1.

That is, in the moving to the first point P1 (S50), the robot 100 may move from the current position CP to the first point P1 via the center point P2 of the pattern P.

In the moving to the first point P1 (S50), the robot 100 may move by the radius r of the pattern P by rotating a traveling direction in a direction toward the center point P2 by 90 degrees, and then, move by the radius r of the pattern P by rotating the traveling direction in a direction toward the first point P1 in correspondence with the angle difference 8 between the center point P2 and the first point P1.

In the moving to the charging station 500 (S60), the robot 100 may move from the first point P1 to the charging station 500 by a distance between the robot 100 and the charging station 500.

Accordingly, the robot 100 may return to the charging station 500 in a shortest distance determined by the pattern traveling.

The moving method can be implemented as computer-readable codes on a program-recorded medium, wherein the moving method includes the starting of the pattern traveling (S10), the determining of the distance information (S20), the setting as the first point P1 (S30), the returning to the current position CP (S40), the moving to the first point P1 (S50), and the moving to the charging station 500 (S60). The computer-readable medium includes all kinds of recording devices in which data readable by a computer system is stored. Examples of the computer-readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device and the like, and may also be implemented in the form of a carrier wave (e.g., transmission over the Internet). In addition, the computer may also include the controller 20.

The above-described embodiments of the moving robot, the moving robot system, and the method for moving the moving robot to the charging station according to the present disclosure may be implemented independently or in a combination of one or more embodiments. In addition, the above-described embodiments may be applied to a control element of the moving robot, the moving robot system, a control system of a moving robot, a method for controlling a moving robot, a method for moving a moving robot to a charging station of the moving robot, and a method for controlling moving of a moving robot to the charging station of the moving robot, in a combination of particular embodiments. In particular, the above-described embodiments may be usefully applied and implemented with respect to a moving robot, a control system of a moving robot, a method for controlling a moving robot, a method for controlling moving of a moving robot, a method for returning, by a moving robot, to a charging station, etc.

While the present disclosure has been particularly shown and described with reference to embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the following claims. Therefore, the scope of the present disclosure is defined not by the detailed description of the embodiments, but by equivalents of the appended claims as well as the appended claims.

While the present disclosure has been particularly shown and described with reference to exemplary embodiments, described herein, and drawings, it may be understood by one of ordinary skill in the art that various changes and modifications thereof may be made. Accordingly, the scope of the present disclosure should be defined by the following claims, and various changes equal or equivalent to the claims pertain to the category of the concept of the present disclosure. 

What is claimed is:
 1. A moving robot comprising: a main body; a driving unit that moves the main body; a receiver that receives a transmission signal transmitted from a charging station in a travel area; and a controller that controls traveling of the main body by controlling the driving unit so that the main body travels in the travel area, based on at least one selected from a reception result of the transmission signal and an area map that is pre-stored, wherein the controller, when the controller controls the main body to move to the charging station, estimates information about a distance between the main body and the charging station based on the reception result of the transmission signal received while the main body travels in a pattern that is preset, by controlling the main body to travel at a current position in the pattern, and controls the main body to move to the charging station according to the moving path by determining a moving path for moving to the charging station based on the distance information.
 2. The moving robot of claim 1, wherein the pattern is a pattern having the current position as both a start point and an end point.
 3. The moving robot of claim 2, wherein the pattern is a pattern constituting at least one closed curved surface.
 4. The moving robot of claim 3, wherein the pattern is a circular pattern with a predetermined radius.
 5. The moving robot of claim 1, wherein the controller determines the moving path based on the distance information at respective points of a path according to the pattern by estimating the distance information at the respective points of the path according to the pattern based on the reception result during the traveling in the pattern, and controls the main body to move to the charging station according to the moving path.
 6. The moving robot of claim 5, wherein the controller determines the moving path to minimize a moving distance to the charging station based on the distance information at the respective points.
 7. The moving robot of claim 6, wherein the controller determines a path from a point to the charging station as the moving path, the point having the distance information as being nearest the charging station among the respective points.
 8. The moving robot of claim 7, wherein the controller sets, as a first point, the point having the distance information as being nearest the charging station among the respective points, and sets a center point of the pattern as a second point to thereby determine a path corresponding to a line including the first point and the second point as the moving path.
 9. The moving robot of claim 8, wherein the controller sets, as a third point, a point having the distance information as being farthest from the charging station among the respective points, and sets an intermediate point between the first point and the third point as the second point.
 10. The moving robot of claim 7, wherein the controller sets, as the first point, the point having the distance information as being nearest the charging station among the respective points, sets, as a third point, a point having the distance information as being farthest from the charging station among the respective points, and determines a path corresponding to a line including the first point and the third point as the moving path.
 11. The moving robot of claim 7, wherein the controller, after the traveling according to the pattern is finished, controls the main body to move from the current position to the point having the distance information as being nearest the charging station via a center point of the pattern, and move from the point having the distance information as being nearest the charging station to the charging station along the moving path.
 12. The moving robot of claim 11, wherein the controller, when the controller controls the main body to move to the point having the distance information as being nearest the charging station, controls the main body to move by a radius of the pattern by rotating a traveling direction in a direction toward the center point by 90 degrees, and then, move by the radius of the pattern by rotating the traveling direction in direction of the point in correspondence with an angle difference between the center point and the point having the distance information as being nearest the charging station.
 13. The moving robot of claim 7, wherein the controller determines the moving path so that a traveling direction of the main body is within a predetermined range with reference to the charging station.
 14. A moving robot system comprising: a charging station that is provided in a travel area and transmits a transmission signal for determining position information; and a moving robot that travels in the travel area based on at least one selected from a reception result of the transmission signal and a prestored area map, wherein the moving robot, when the moving robot returns to the charge station, travels at a current position according to a path that is preset, estimates information about a distance between the moving robot and the charging station based on a reception result of the transmission signal received during the traveling according to the pattern, determines a moving path for moving to the charging station based on the distance information, and moves to the charging station via the moving path.
 15. The moving robot system of claim 14, wherein the moving robot travels in a pattern forming at least one closed curved surface.
 16. The moving robot system of claim 14, wherein the moving robot determines the moving path based on the distance information at respective points of the path by estimating the distance information at the respective points of the path according to the pattern based on the reception result during the traveling in the pattern, and moves to the charging station according to the moving path.
 17. The moving robot system of claim 16, wherein the moving robot determines a path from a point to the charging station as the moving path, the point having the distance information as being nearest the charging station among the respective points.
 18. The moving robot system of claim 16, wherein the moving robot, after the traveling according to the pattern is finished, moves from the current position to a point having the distance information as being nearest the charging station via a center point of the pattern and moves from the point having the distance information as being nearest the charging station to the charging station.
 19. A method for moving to a charging station of a moving robot, wherein the moving robot comprises: a main body; a driving unit that moves the main body; a receiver that receives a transmission signal transmitted from a charging station in a travel area; and a controller that controls traveling of the main body by controlling the driving unit so that the main body travels in the travel area, based on at least one selected from a reception result of the transmission signal and an area map that is pre-stored, the method comprising: starting pattern traveling at a current position according to a preset closed-loop pattern; determining information about a distance between the main body and the charging station based on a reception result of the transmission signal during the pattern traveling; setting a point nearest the charging station, among points of a path of the pattern traveling, as a first point; returning to the current position by finishing the pattern traveling; moving from the current position to the first point; and moving from the first point to the charging station.
 20. The method of claim 19, wherein the moving from the current position to the first point comprises moving from the center point to the first point, after moving from the current position to a center point of the preset closed-loop pattern. 